1. Field of the Invention
The present invention relates generally to devices for blowing air across the surface of vehicles in order to dry moisture from such vehicles, and more particularly to a vehicle dryer that uses less power, and conserves energy.
2. Description of the Related Art
Automated vehicle washing systems have been available for many years to automatically wash and dry vehicles. Large volume vehicle washing systems typically include a conveyor system for moving a vehicle through a series of washing and rinsing stations, and finally, through a drying station which serves to remove moisture from the surface of the vehicle. Vehicle dryers are also commonly found within in-bay roll-over washing systems and in drive-through fleet vehicle washing systems.
A variety of drying stations are known for removing moisture from the vehicle. Touch-free drying stations often use one or more blower fans that supply blown air to dry the surfaces of the vehicle. In some cases, the blown air may be directed through ducts to vents positioned along the sides and above the path of the vehicle. In other cases, air discharged from the blower fans is immediately directed at the vehicle without intervening ducts or vents; such blower fans may either be fixed or oscillating. Oscillating blower fans better ensure adequate coverage for vehicles having a wide variety of contours.
Oftentimes these blower fans require motors rated at ten horsepower or more per fan to supply the proper rate of air flow. Such electric motors may be operated from a 220V AC electrical supply and may draw as much as 30 amps of current to rotate such blower fans, which typically rotate at speeds of 3,450 RPM. Such blower fans typically create an airflow rate of approximately 4,000 cubic feet per minute per fan. The operation of such blower fans can consume a significant amount of electrical power.
There are significant periods of time during the operation of a car wash facility during which there is no demand for blown air, e.g., periods when no vehicle is present within the car wash facility. One way to temporarily reduce power consumption is to turn off such blower fans when vehicles are not present. However, frequent starts and stops take a toll on electric motors and reduce their useful life. In addition, starting and stopping electric blower fan motors is not an effective way to reduce total power consumption. When such motors are initially started up, they draw much more electrical current before coming up to speed as compared to the amount of current drawn after the motor has reached normal operating speed. Accordingly, it is often preferred to allow such blower motors to run continuously during normal business hours, both to reduce overall electrical power usage and to reduce required maintenance for the electric motor.
Those skilled in the art have suggested several approaches to address the above-stated problems. For example, in U.S. Pat. No. 4,836,467 to Rodgers, a rotatable valve plate is inserted in the outlet of the blower fan assembly and is controlled by a solenoid. When a vehicle is present, this outlet valve is opened; when no vehicle is present, this outlet valve is closed. Rodgers reports a reduction of current from 100 amps with the outlet valve opened to approximately 40 amps with the outlet valve closed. Likewise, in U.S. Pat. No. 6,449,877 to Cote, et al., a rotatable control damper, or airfoil, is positioned between the outlet of a blower and a duct used to direct the blown air toward the vehicle. Cote's control damper is used to adjust the amount of air delivered in accordance with the type and profile of the vehicle to be dried.
Another method of decreasing the load on the fan motor when a vehicle is not present is to restrict air flow at the inlet of the fan. Blocking air at the inlet of the fan starves the fan of air, creates lower pressure within the fan housing, and reduces the load on the fan impeller. This relative vacuum allows the fan to rotate with less effort, thus decreasing the power required to keep the fan turning. In U.S. Pat. No. 7,284,296 to McElroy discloses a sliding valve plate disposed over the inlet of a blower housing to control the amount of air sucked into the inlet. The valve plate slides along a pair of rails, and a hydraulic cylinder moves the valve plate between its opened and closed positions. However, this sliding valve plate mechanism is relatively large and cumbersome, prone to mechanical breakage, requires significant force to open the valve, and is incompatible with many fan and blower types.
U.S. Pat. No. 7,565,753 to Christopher discloses a vehicle dryer assembly that includes a blower unit having an inlet and an outlet. A series of louvers are disposed at the inlet of the blower unit; the louvers are moveable between an open position and a closed position. A hydraulic cylinder is mechanically coupled to the louvers to move the louvers between their open and closed positions. Once again, this disclosed louver assembly is relatively large, and significantly increases the size of the blower housing. Christopher's louver assembly includes a number of moving parts that can break or bind, and is not easily adapted to many fan and blower types. In addition, Christopher's inlet plenum 20 is square, rather than circular, in order to accommodate Christopher's slatted louvers, which introduces a discontinuity in the air flow to the inlet of the generally circular blower housing.
MacNeil Wash Systems Ltd. of Barrie, Ontario, Canada has marketed an air valve under the trademark “Power Lock” which mounts over the inlet of a vehicle dryer. The valve assembly moves between an opened position spaced away from the inlet of the blower housing, and a closed position directly adjacent the inlet of the blower housing. Movement of the valve is controlled by routing pressurized air to the valve assembly. The valve assembly moves along an axis parallel to the axis of the fan motor. Promotional literature distributed by MacNeil Wash Systems Ltd. claims a reduction in motor horsepower of 50% when the valve is closed compared to when the valve is open. While such a device is helpful in reducing energy consumption, MacNeil's air valve device appears to impose a restriction in the incoming airflow when the valve is open. MacNeil's air valve device also adds approximately another twelve inches to the overall depth of the blower housing. In addition, MacNeil's air valve device appears to require a relatively large air pressure (approximately 40 psi) to move the air valve between its opened and closed positions.
It is therefore an object of the present invention to provide a vehicle dryer that can significantly reduce air pressure within the blower housing of the vehicle dryer during times when air flow is not needed, while allowing the fan to continue running during such times.
It is a further object of the present invention to provide such a vehicle dryer adapted to significantly reduce power consumption during times when air flow is not needed, while avoiding the need to power the motor off and back on.
It is a yet further object of the present invention to provide a mechanism to selectively block air flow at the inlet of a vehicle dryer that may be used with multiple types of vehicle dryers.
It is another object to provide such a vehicle dryer that is simple to operate, easy and inexpensive to construct, relatively compact, and which requires relatively few moving parts.
It is still another object of the present invention to provide a vehicle dryer that can quickly and easily be switched between high air flow and virtually no air flow while leaving the fan running continuously, while being capable of being operated with relatively low pneumatic actuation pressure.
Yet another object of the present invention is to provide such a vehicle dryer which avoids any significant discontinuities and/or restrictions in the path of air entering the blower housing when blown air is desired at the outlet of the vehicle dryer.
These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds.